Answer:
0.02906
Step-by-step explanation:
number of questions =30
getting exactly right : 12
30C12 the number of possibilities
probability to get it right (1/4)^12
probability of failure =1-1/4=(3/4)^18 ( 18 = 30 questions -12 right )
P(12)=30C12*(1/4)^12*(3/4)^18=0.02906
hope it helps